Sciatica pain is the chronic pain in the lower lumbar and lumbosacral spine. Sciatica pain radiates along the path of the sciatica nerve. It starts from the lower back to the hips and buttocks and radiates to the legs. Sciatica most commonly occurs when a herniated disk or a bone spur on the spine compresses part of the nerve. This causes inflammation, pain and often some numbness in the affected leg.